Slashdot videos: Now with more Slashdot!

View

Discuss

Share

We've improved Slashdot's video section; now you can view our video interviews, product close-ups and site visits with all the usual Slashdot options to comment, share, etc. No more walled garden! It's a work in progress -- we hope you'll check it out (Learn more about the recent updates).

An anonymous reader writes with news from Geek.com on an expansion board for the Raspberry Pi. Quoting: "In the middle of December last year the Raspberry Pi Foundation made a surprising announcement that not only would we see the $25 PC released in 2012, it would also be getting an expansion board ... called the Gertboard, and is being developed by Broadcom employee Gert van Loo in his spare time. When completed, it will allow Raspberry Pi owners to play around with flashing LEDs, electric motors, and a range of different sensors. It effectively takes the $25 Raspberry Pi beyond just being a very cheap PC. There's a video of the Gertboard already working which demonstrates the 12 LEDs being lit up and the board powering an electric motor more than capable of lifting something like your garage door."

Who are these people who keep on insisting on using through-hole components? That board could easily be the same size as the Raspberry-pi board itself simply by using SOIC packages as opposed to DIP for all of the ICs. Soldering a 1.27mm pitch SMT component is really easy, it takes about the same amount of time as a DIP component, and is much, much, smaller.

I understand from the Raspberry-pi website that it's gonna be supplied as a bare board + components, but like I said, soldering SMT stuff is really easy. Also if the whole point of this Raspberry-pi stuff is to teach people new skills, why not teach them how to solder stuff that the rest of the world is now using.

I know, it's great and all, but if you're using the pi to do the heavy lifting, and the gert as simply a way to output, doesn't an arduino already do this, and with linux too? Is this redundant, or have I missed something?

They have 13$ arduinos... That said, I prefer a Linux machine that can run python, java, apache and everything and then just talk to some IO library or something to take care of moving motors etc.But that's because I am a software guy....

Uuum, I looked at those sites. And all I see is "in the pipeline", "if you have any ideas", "mailing list" and "could potentially be developed as X".There are no ways to order anything, not even a name to call whatever they are doing. Not even pictures.

Either I overlooked something, or this is the king of vaporware and hasn't passed the "Well, we thought it would be cool to have X. But we haven't anything more to offer." stage.

Can you point me to a link where I can put my money and get a Raspberry-Pi-like board that I can plug my keyboard, display, sound, storage and network into, and install Linux on?

I've soldered plenty of SM components myself, but you may be overlooking the novice oriented aspects of this system (and the comments you dismiss), especially when it comes to the tools available. Besides, practice only takes you so far; even an experienced plastic surgeon may have a hard time making something look pretty if he's only got leather-working tools available.

If you consider that the computer is marketed as cheap, and this board is an educational add on (presumably also cheap) (well the board is functional, but the article points out the educational advantages, including the population), then it would probably be safe to assume that the soldering iron will also be cheap. A soldering iron allowing comfortable SM work is easily double or triple the cost of the computer - over an order of magnitude for the good ones. So, if one were to use a soldering iron of comparable or less cost than the system (what a novice may choose to start with), SM could be very hard if not impossible.

Arduino and Raspberry Pi are not competators in any way. They target two different markets whereby they have very slight overlap for hobbiests. The Pi simply can not compete with Arduino/AVR on the low end and Arduino/AVR can not compete with RPi on the highend. There's only a tiny intersection between the two and that's likely only because you have one or the other whereby a "close enough" solution is satisfactory.

AVR/Arduino has solutions in the $1-$6 range, if you want to use an inexpensive ISP [ebay.com] and break out the coresponding pins on your bare bones [moderndevice.com] or really bare bones [solarbotics.com] controller. Not to mention, the pins are easy to access with a multitude of more pins available. It also has some capabilities which are simply not available without a Gert board, which makes the pi all the more expensive. Furthermore, an RPi is basically as barebones as you're going to see - at least for a while - if ever. Whereas for the AVR/Arduino solution makes it easy to transplant your Arduino project into a barebones $3-$9 project.

Furthermore, these two projects are really far and away much more complimentary technologies than they are competators. Basically, let the RPi do the heavy CPU lifting and the AVR's do the GPIO and bit flipping. Its a combination made in heaven.

You know, to set the value of a GPIO pin on an Arduino you just make a single call to digitalWrite(). To trigger a stepper motor you have to toggle the pin's value, which requires (gasp!) two calls to digitalWrite. The equivalent under Linux involves opening the GPIO device file and making multiple read and write calls. For anyone who's ever run a stepper motor using an Arduino the overhead involved in all that boggles the mind. Really, ease of access to the GPIO pins is the least of your considerations when comparing Arduino to RaspberryPi.

For embedded applications involving motors and servos the Achilles heel of Linux is real-time control. If you Google around for projects which use Linux boards for motor control you'll find people discussing wobbly servos and problems with interrupt latency. There are hacks which add a real-time layer under Linux but in general they have not been embraced by the Linux distros and are not well supported.

I've done a few Arduino projects involving stepper motors and servos. My latest project requires much more than an Arduino can deliver so I'll be using a BeagleBoard running Linux. The motion logic will be offloaded to an Arduino and the two boards will talk to each other over a serial line. This sounds complicated but it will be much easier to maintain than a custom RTOS Linux hack and will give us complete and control over the timing aspects of the motors and servos.

Frankly, comparing Arduino to something like a BeagleBone or RaspberryPi baffles me. They are very different devices with very different applications. For most of my Arduino projects Linux would have added nothing of value. And for my latest project a bare Arduino wasn't nearly powerful enough. Entirely different worlds.